Breathalyzer tests are the most common methods in determining if someone is driving under the influence of alcohol. While California law does not require a suspect to submit to a breathalyzer test, many people do not realize this and will take one if pulled over under the suspicion of DUI. However, the accuracy of breathalyzer tests have been called into question in recent years and this is a defense that many San Francisco DUI attorneys can use when preparing for your day in court.
If a breathalyzer test is the only concrete evidence that someone was driving under the influence of alcohol, then many scientists are beginning to believe this alone is not enough evidence for conviction. There have been cases where there is a discrepancy of up to 15% between the Blood Alcohol Concentration (BAC) found with a breathalyzer test than found with an actual blood test. Several factors can contribute to this discrepancy, including overall physiology as well as gender. Many women process alcohol in their blood differently than men do and different concentration levels can be found. In California, a BAC of .08% or higher is grounds for a DUI charge, but a DUI attorney in San Francisco can argue that the test may not be an accurate reflection of how impaired someone was when they got behind the wheel.
This also can relate to the inaccuracy of an actual blood test, as these tests only measure the concentration of alcohol in the blood and have no way of telling how much of the alcohol actually went to the brain and affected how that person would drive. Field sobriety tests should also be used in conjunction with tests that test BAC. However, the only two tests that experts agree are highly accurate is when a suspect is asked to turn around and also follow a pencil with his or her eyes that the officer is holding.
Also, if you were not drinking at all, but were driving under the influence of drugs—whether illegal or not—then a breathalyzer test is worthless because its only purpose is to detect alcohol. Blood tests must be given to detect drugs and their accuracy can be called into questions as well, depending on when the blood test was administered and a San Francisco DUI lawyer will investigate all aspects on how and why an arrest was made.
It is the job of the prosecution to prove that someone was driving when they legally should not have been and when they were impaired. It is the job of a DUI lawyer in San Francisco to call into question both procedures done at the time of arrest and also tests performed to make sure the defendant was indeed too impaired to drive.